Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 54: Computational Materials Modelling VIII - Mechanical Properties and Strain

MM 54.5: Vortrag

Donnerstag, 29. März 2012, 16:45–17:00, TC 006

Elastic anomalies and short-range order effects for Ag-Pd alloys — •Martin Hoffmann^1,2, Alberto Marmodoro³, Eero Nurmi⁴, Kalevi Kokko⁴, Arthur Ernst², and Wolfram Hergert¹ — ¹Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Von-Seckendorff-Platz 1, D-06120 Halle, Germany — ²Max-Planck-Institut für Mikrostrukturphysik,Weinberg 2, D-06120 Halle, Germany — ³Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom — ⁴Department of Physics and Astronomy, University of Turku, FIN-20014 Turku, Finland

We investigate the elastic properties of the binary alloy Ag-Pd. From the experiment it is known that the lattice constant of this system shows a deviation from the expected linear behaviour according to the Vegard's rule. This was formerly studied by assuming a totally disordered alloy and thereby using the coherent potential approximation (CPA). However, there are predictions of three ordered phases in this system and we include them in our study via supercell calculations. Due to the treatment of certain sub-lattices with the CPA in the Korringa-Kohn-Rostoker formalism we are able to explore the equilibrium properties even in the concentration range between the long-range order structures. We obtain again various deviations from the linear behaviour. As former studies assumed such changes could be observed in concordance with electronic topological transitions in the Fermi surface topology. Using the novel concept of the multi sub-lattice non-local CPA we introduce short-range order within the same supercell construction.